632 Original Articles. [ Oct., 
Tas_e I.—First Series of Experiments on Absorption, under a Pressure of 20,000 lbs. 
per square inch, reduced to 100 hours’ exposure and 10 inches area. 
Reduced results. 
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1 India-vubber - 2 2 = 120300082720) |) 1100) |) VON NOs 
2 India-rubber with carbon. | 20,000 | 8°720 | 100} 10 | 0-055 
3 Wray’s compound . . . | 20,000 | 8-720] 100} 10 | 0-072 
4 Gutta-percha. . . . . | 20,000 | 8-720 | 100] 10 | 0-044 
rubber. The pure india-rubber appears to combine superficially with 
water as the surface becomes white, either at parts, in the present expe- 
riment, or over the whole surface. The carbon appears to prevent the 
formation of this hydrate, and at the same time reduces the elasticity 
of the native rubber, and enables it to be worked more kindly. 
In the next series, the whole of the specimens were placed in the 
same cylinder, Fig. 1, and remained under pressure during the same 
period and under the same conditions. 
Taste Il.—Haperiments on Absorption, under a Pressure of 6,000 lbs. and at the 
Ordinary Temperature. 
Results reduced to 10 inches area. 
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1 India-rubber, unmasticated | 5,900 | 2°575 450 10 | 3:075 
4 India-rubber, masticated . | 5,900 | 2°575 450 10 | 0-028 
8 _ 5 3 5,900 | 2°575 450 10 0°636,N 
9 * o . | 5,900 | 2°575 | 450] 10 | 0-700 tS 
10 5 55 ~ | 95 900))) 22575) |) 450) LO Olas 
11 India-rubber, vuleanized . | 5,900 | 2°575 | 450 10 0°146 
7 India-rubber, carbonized . | 5,900 | 2°575 450 10 0:980 
2 Gutta-percha . . .. . | 5,900 | 2°575 | 450) 10 | 0°378 iS 
13 45 5 EMR sae de iaee 5,900 | 2°575 450 10 0-178 
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5 Wray’scompound .. . | 5,900} 2°575 | 450] 10 | 0-750 \s 
13 i Bs . + . | 5,900 | 2-575 | 450] 10 | 0-700 2 
6 Chatterton’s compound . | 5,900 | 2°575 | 450 | 10 | 0°375 = 
12 i us 5,900 | 2°575 | 450 10 | 0°183 = 
| 
